This section is in development; I'll be adding to it as I research and find accurate information to help us understand not only terminology but the structure of the USMC units as well.
Thank you MJ, a MarineParents.com volunteer, for your excellent assistance and finding the following information for all of us:
For great information on the organization and structure of the Marine Corps, see the USMC Publication Marine Corps Concepts and Programs. Here's a link to a USMC page that has some PDF files that are an oustanding resource:
http://hqinet001.hqmc.usmc.mil/p&r/concepts/2004/TOCA.HTM
CAAT: Combined Anti-Armor Team
(They work in a humvee and have 50 cal machine guns and tow missiles and mk 19 which are automatic grenade launchers. Javelins are employed with CAAT teams. CAAT Red and CAAT blue are two different platoons, they call them by colors instead of numbers.)
Field Artillery Units are not referred to as a Company; they are called a "Battery". As an example, E Btry 2Bn 11th MAR. You will know this is a Field Artillery Unit where "E" is the "Battery" rather than a company name.
Structure of a Regiment:
5 Marines to a Fire Team (5)
3 Fire Teams to a Squad (15)
4 Squads to a Platoon (60)
4 Platoons to a Company (240)
5 Companies to a Battalion (1200)
5 Battalions to a Regiment (6000)
7th Marine Regiment:
3/4: 3rd Battalion, 4th Marines (a/k/a Thundering Third)
(Includes the following companies: India, Kilo, Lima, Weapons)
3/7: 3rd Battalion, 7th Marines
3/11: 3rd Battalion, 11th Marines
2/7: 2nd Battalion, 7th Marines
I believe H&S (Headquarters & Supply) is part of this as well, though they may be referred to as HQ, not to be confused with an HQ Platoon though.)